JPH06140957A - U-v tuner - Google Patents

Abstract

PURPOSE:To prevent crosstalk due to a disturbing signal from a VHF circuit receiving a VHF signal on the reception of a UHF signal. CONSTITUTION:An input side of a high frequency amplifier circuit 22 receiving a signal from an input tuning circuit 21 of a VHF circuit 20 receiving a VHF signal is connected to ground via a series circuit comprising a bypass capacitor C2 and a switching diode SD2 whose cathode is connected to the input side of the circuit 22 and a connection part between the bypass capacitor C2 and the switching diode SD2 is connected to a power supply terminal UHF+B of a UHF circuit 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a VH which receives a VHF signal.
It is equipped with an F circuit and a UHF circuit that receives UHF signals.When receiving a UHF signal, the frequency mixing circuit to which the VHF signal from the VHF circuit is input is used as an intermediate frequency amplification circuit for the UHF signal. The present invention relates to a V tuner device.

[0002]

2. Description of the Prior Art Television and video recorders include
It is equipped with a UV tuner device which is connected to an antenna input terminal provided on it and comprises a VHF circuit for receiving a VHF signal and a UHF circuit for receiving a UHF signal. This U-V tuner device uses a frequency mixing circuit to which the VHF signal from the VHF circuit is input as an intermediate frequency amplifying circuit for the UHF signal when receiving the UHF signal. In that case, upon reception of the UHF signal, interference signals in the frequency band of the VHF signal passing through the VHF circuit or interference by the active circuits in the VHF circuit using these signals as interference sources may occur.

Therefore, a tuner device for a television receiver which prevents such interference interference is disclosed in Japanese Utility Model Publication 57.
-10123 bulletin, electronic tuning tuner is also in Japanese Examined Sho 60-4
Each is disclosed in the 6895 publication.

FIG. 1 is a block diagram showing the configuration of the tuner device of the former television receiver. 100 is a VHF tuner, 101 is a UHF tuner, 102 is a VHF signal input terminal,
103 is a UHF signal input terminal. The VHF tuner 100 includes a high frequency circuit 104, a local oscillator circuit 105, and a frequency mixing circuit 106.
The high frequency circuit 104 includes an input tuning circuit 107, a high frequency amplifier circuit 108, an interstage primary side tuning circuit 109, and an interstage secondary side tuning circuit 110. And each tuning circuit 107,10
9,110 is a variable capacitance diode 112,113,11 whose capacitance value is determined by the DC voltage from the tuning voltage supply terminal 111.
4 and the first coils 115, 116 and 117 and the second coil which form tuning together with the variable capacitance diodes 112, 113 and 114.
Switching diodes 121, 122, 123 are provided which make 118, 119, 120 and the second coil 118, 119, 120 short-circuited during VHF high band reception to render them inoperative.

Both the switching diode 121 of the input tuning circuit 107 and the switching diode 123 of the interstage secondary side tuning circuit 110 have anodes of the VHF tuner 100.
It is connected to the operating power supply terminal 124 of the frequency mixing circuit 106. The anode of the switching diode 122 of the interstage primary side tuning circuit 109 is the operating power supply terminal 125 of the high frequency amplification circuit 107 and the local oscillation circuit 105 of the VHF tuner 100.
Connected with. Switching diode 121,122,12
All 3 cathodes have a common band switching signal supply terminal 126
Connected with. Switching diode 130 is UHF
When receiving a signal, it conducts and the intermediate frequency signal of the UHF tuner 101 is input to the frequency mixing circuit 106 of the VHF tuner 100. Conversely, when receiving a VHF signal, it becomes non-conducting and the connection circuit between the UHF tuner 101 and the VHF tuner 100. It is designed to shut off. 131 is an operation power supply terminal of the UHF tuner 101.

This tuner device sets the input tuning circuit 107 and the interstage secondary side tuning circuit 110 of the VHF tuner 100 to the VHF high band when receiving the UHF signal.
Set the interstage primary side tuning circuit 109 to VHF low band,
The interfering signal from the VHF tuner 100 is prevented from being transmitted to the frequency mixing circuit 106 functioning as an intermediate frequency amplifying circuit for the UHF signal.

FIG. 2 is a block diagram showing the configuration of the latter electronic tuning tuner. 200 is VHF signal input terminal, 201 is
UHF signal input terminal, 202 is intermediate frequency signal output terminal, 203
Is a filter, 204 is a high frequency amplifier circuit, 205 is a local oscillator circuit, 206 is a frequency mixing circuit, 207 is a UHF tuner, 208,
209… 216 is a tuning coil, 217,218,219 is a variable capacitance diode, 220,221,222,223,224 is a switching diode, 225,226… 232 is a resistor, 233,234… 244 is a capacitor, 250 is an operating power supply terminal for a UHF tuner, and 251 is VH.
F High-band operation power supply terminal, 252 is VHF low-band operation power supply terminal, 253 is tuning voltage supply terminal, 254 is operation power supply terminal of frequency mixing circuit, and 255 is test probe terminal.

A resistor 232 interposed between the power supply terminal 250 and the power supply terminal 251 makes it possible to set the connection point B to a predetermined voltage and apply a predetermined voltage to the anodes of the diodes 220, 221, 222, 223. This tuner has a high resistance value when receiving UHF signals.
The switching diode 220 of the input tuning circuit of 260, the switching diode 222 of the interstage primary side tuning circuit, and the switching diode 223 of the interstage secondary side tuning circuit are made to flow through a minute current to make these switching diodes a damper resistor. The VHF circuit 260 attenuates the amount of interference signals transmitted to the frequency mixing circuit 206.

[0009]

However, according to the former tuner device of the television receiver, the switching bias of each stage of the tuning circuit in the VHF circuit becomes complicated, and the circuit configuration is difficult. If the bias condition is not carefully determined, the active circuit of the VHF circuit, for example, the high frequency amplifier circuit may operate in the non-linear region even though the UHF signal is received through the bias line. According to the latter electronic tuning tuner, the non-linear region of the switching diode is used because the current flowing through the switching diode is very small.
There is a risk of generating harmonic interference signals.

Further, in these tuner devices and tuners, when considering the interfering signal level selected by the input tuning circuit at the time of receiving a UHF signal, in the former case, as shown in FIG. It is almost the same and does not attenuate around 200MHz. In the latter case, as shown in FIG. 4, the damping effect is larger than in the former case due to the damping effect of the switching diode.
In the vicinity of 0MHz, there is no choice but to be in a state where the attenuation is not sufficient.

Therefore, in any of the above-mentioned tuners, when the UHF signal is received, the interference signal selected by the input tuning circuit of the VHF circuit is not sufficiently attenuated over the entire frequency range, and is connected to the input tuning circuit. It is necessary to take complementary measures such as interstage tuning circuit. In addition, there is a possibility that high-order distortion, beat interference, etc. may occur due to the high-frequency amplifier circuit that becomes a non-linear bias state depending on the bias state of the switching diode, and that interference interference cannot be completely eliminated when a UHF signal is received. There's a problem. In view of such a problem, the present invention provides a U-V tuner device which does not cause interference due to an interference signal transmitted to a VHF circuit and a harmonic interference signal caused by the VHF signal when a UHF signal is received. To aim.

[0012]

A U-V tuner device according to the present invention comprises a VHF circuit for receiving a VHF signal and a UHF circuit for receiving a UHF signal, and when receiving the UHF signal, the VHF circuit from the VHF circuit is received. In a U-V tuner device in which a frequency mixing circuit to which a signal is input is used as an intermediate frequency amplifying circuit of a UHF signal, a signal input terminal of the high frequency amplifying circuit of the VHF circuit and power supply of the UHF circuit. A diode connecting an anode to the power supply terminal is interposed between the terminal and the terminal, and an anode side of the diode is grounded via a bypass capacitor.

[0013]

[Function] When receiving a UHF signal, the received UHF signal
Intermediate frequency amplification is performed by the frequency mixing circuit that is located after the high-frequency amplification circuit of the VHF circuit. The diode is turned on by the voltage applied to the power supply terminal of the UHF circuit. The interference signal transmitted to the VHF circuit and the interference signal generated by the VHF circuit are bypassed to the high frequency amplification circuit through the series circuit of the diode connected to the input side of the high frequency amplification circuit of the VHF circuit and the bypass capacitor. No interfering signal is input. This prevents interference due to interfering signals from the VHF circuit when receiving the UHF signal.

[0014]

The present invention will be described in detail below with reference to the drawings showing the embodiments thereof. FIG. 5 is a block diagram showing the configuration of the UV tuner device according to the present invention. VHF circuit 20 is input tuning circuit 2
1. A high frequency amplifier circuit 22 and an interstage tuning circuit 23. The common antenna terminal 26 to which the VHF signal and the UHF signal are input is connected to the input tuning circuit 21 of the VHF circuit 20 and each input side of the UHF circuit 27. The output side of the input tuning circuit 21 is connected to the input side of the high frequency amplifier circuit 22, and the output side thereof is connected to the input side of the interstage tuning circuit 23. Interstage tuning circuit 23
The output side of is connected to the VHF signal input side of the frequency mixing circuit 24.

The output side of the local oscillator circuit 25 is a frequency mixing circuit.
Connected to 24 oscillation signal input side. The output side of the UHF circuit 27 is connected to the UHF signal input side of the frequency mixing circuit 24. The output side of the frequency mixing circuit 24 is connected to the input side of the intermediate frequency amplifier circuit 28, and the output side thereof is connected to the intermediate frequency signal output terminal 29. The input tuning circuit 21, the high-frequency amplifier circuit 22, the interstage tuning circuit 23, and the local oscillation circuit 25 are connected to a power supply terminal VHF _{+ B} that gives a voltage for operating them. The frequency mixing circuit 24 and the intermediate frequency amplifier circuit 28 are connected to a power supply terminal MB that gives a voltage for operating them. UHF circuit 27 is a power supply terminal that provides the voltage to operate it UHF
Connected to _{+ B.} The input side of the high frequency amplifier circuit 22 is grounded via a series circuit of a switching diode SD ₂ and a bypass capacitor C ₂ whose cathodes are connected to it. A connecting portion between the switching diode SD ₂ and the bypass capacitor C ₂ is connected to a power supply terminal UHF _{+ B} which gives a voltage for operating the UHF circuit 27.

FIG. 6 is an actual circuit diagram of a portion surrounded by a broken line in FIG. 5, that is, a portion including the input tuning circuit 21, the high frequency amplifier circuit 22, the bypass capacitor C ₂ , the switching diode SD ₂ and the power supply terminal UHF _{+ B.} is there. Common antenna input terminal 26 for VHF signals and the UHF signal is input is grounded through a series circuit of a filter F and the inductor L _10, L _11. The connection portion between the filter F and the inductance coil L ₁₀ is grounded via the series circuit of the capacitor C ₁₀ , the inductance coils L ₁₂ and L _13, and the capacitor C ₁₁ . The connecting portion between the inductance coils L ₁₂ and L ₁₃ is connected via the resistor R ₁₀ to the power supply terminal VL _{+ B} which gives a voltage for operating the VHF low band, and the connecting portion between the inductance coils L ₁₂ and L _13. Is a high-frequency amplifier circuit 22 via a series circuit of a switching diode SD ₁ having a cathode connected to the capacitor C ₁₂ , a inductance coil L ₁₄ and a coupling capacitor C _1.
Is connected to the gate G _{1 of the} FET Q constituting the.

The connecting portion between the capacitor C ₁₂ and the inductance coil L ₁₄ is connected via the inductance coil L ₁₅
It is connected to the connection between the inductance coils L ₁₀ and L ₁₁ . The connection between the switching diode SD ₁ and the capacitor C ₁₂ is connected via a resistor R ₁₁ to a power supply terminal VH _{+ B} which gives a voltage for operating the VHF high band. The connecting portion between the inductance coil L ₁₄ and the coupling capacitor C ₁ has a varactor diode VD ₁ having an anode connected thereto.
And the capacitor C ₁₃ are grounded via a series circuit, and the connection between the varactor diode VD ₁ and the capacitor C ₁₃ is a resistor R.
Connected via ₁₂ to the tuning voltage terminal TU.

The connecting portion between the coupling capacitor C ₁ and the gate G ₁ is connected to the power supply terminal UHF _{+ B} for giving a voltage for operating the UHF circuit 27 via the switching diode SD ₂ having the cathode connected thereto. It The connection between the switching diode SD ₂ and the power supply terminal UHF _{+ B} is grounded via the bypass capacitor C ₂ . Further, the connecting portion between the coupling capacitor C ₁ and the gate G ₁ is connected via the resistor R _1.
Power supply terminal that provides the voltage to operate the VHF circuit 20 VHF
_It is connected to _{+ B} and grounded via a resistor R ₂ . Gate Q _{2 of} FET Q is an automatic gain control (AGC) circuit via resistor R _13.
Connected with AGC. The source S of the FET Q is grounded via the parallel circuit of the resistor R ₁₄ and the capacitor C _14, and the drain D
Is connected to the input side of the interstage tuning circuit 23.

Next, the operation of this UV tuner device will be described.
To do. Now, power supply terminal UHF_{+ B}Voltage to the UHF signal
Switching diode SD when receiving signal₂Is conducting
It becomes a state. In this state, input tuning circuit 21 of VHF circuit 20
The pass-through signal passes through the bypass capacitor C₂Through
The gate of the FET Q that is grounded and constitutes the high-frequency amplifier circuit 22.
G₁Is not input to and is not transmitted to the circuit in the subsequent stage. one
Power supply terminal VHF _{+ B}And power supply terminal VL_{+ B}Or VH_{+ B}To
Gate G of FET Q when voltage is applied and VHF signal is received
₁Switching diode SD due to bias₂Is non-leading
There is no effect on the original transmission of VHF signals.

At the time of receiving the UHF signal, regardless of whether the state of the switching diode SD ₁ is conducting, non-conducting or non-linear, an interference signal generated by the input tuning circuit 21 of the VHF circuit, for example, due to the varactor diode VD ₁ or , Any interfering signal that has passed through the input tuning circuit 21 is switched to the switching diode SD ₂ and the bypass capacitor C.
Can be removed by bypassing through ₂ . Therefore, as in the prior art, it is not necessary to flow a weak current to the switching diode SD _1, it is not constraining the switching diode SD _1. Therefore, switching diode SD ₁
There is also no need to configure a complicated switching bias circuit due to the constraint of.

When the UHF signal is received, a bias voltage is applied to the gate G ₁ of the FET Q by making the switching diode SD ₂ conductive, and the drain D and the source S of the FET Q are normally biased. It is in a non-conducting state because it is not in operation and is in a non-operating state. Therefore, the high frequency amplifier circuit 22 becomes inoperative. Further, since no voltage is applied to the power supply terminal VHF _{+ B} when receiving the UHF signal, no circuit portion of the VHF circuit operates. As a result, when receiving UHF signals, interference signals due to distortion such as harmonic interference due to incomplete operation of the VHF circuit are not generated. Furthermore, even in such a state, the disturbing signal that still causes distortion is the switching diode SD.
Bypassing at ₂ , there will be no interfering signal sources.

As a result, the interference signal level selected by the input tuning circuit 21 when receiving the UHF signal becomes as shown in FIG. In FIG. 7, the vertical axis represents the attenuation amount and the horizontal axis represents the frequency, and shows the level change of the interfering signal at the point A connected to the gate G _{1 of the} FET Q. As is clear from this figure, a large amount of attenuation that is substantially constant over the entire frequency range can be obtained. Therefore, the effect on the interfering signal is perfect, and the interfering signal caused by the VHF signal when receiving the UHF signal can be eliminated. Further, as in the conventional case, when receiving a UHF signal, it is necessary to add a complicated circuit to the band switching switching diodes D ₁ , D ₂ and D ₃ of the input tuning circuit 21 and interstage tuning circuit 23 of the VHF circuit. Since the bias circuit is simple, the circuit configuration is easy. However, the effect of removing the interfering signal is perfect and the UHF
There is no interference due to the VHF signal when receiving the signal.

[0023]

As described above in detail, according to the present invention, when the UHF signal is received, the interference signal which has passed through the VHF circuit and the interference signal generated in the VHF circuit are connected to the input side of the high frequency amplifier circuit of the VHF circuit. Since the bypass circuit is configured to bypass the switching diode and the bypass capacitor, the interfering signal is not transmitted to the circuit subsequent to the high-frequency amplifier circuit, and interference interference does not occur when the UHF signal is received. In particular, even in the case of receiving a UHF signal in a high electric field area of a VHF signal, it has an excellent effect that interference is not generated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a tuner device of a conventional television receiver.

FIG. 2 is a block diagram showing a configuration of a conventional electronic tuning tuner.

FIG. 3 is a curve diagram showing an attenuation characteristic of an interference signal in the tuner device shown in FIG.

4 is a curve diagram showing an attenuation characteristic of an interference signal in the tuner shown in FIG.

FIG. 5 is a block diagram showing a configuration of a UV tuner device according to the present invention.

FIG. 6 is an actual circuit diagram of a circuit portion including an input tuning circuit, a high frequency amplifier circuit, and a power supply terminal of a UHF circuit.

FIG. 7 is a curve diagram showing an attenuation characteristic of an interfering signal in the UV tuner device according to the present invention.

[Explanation of symbols]

20 VHF circuit 21 Input tuning circuit 22 High frequency amplifier circuit 23 Interstage tuning circuit 24 Frequency mixing circuit 25 Local oscillation circuit 26 Antenna input terminal 27 UHF circuit SD ₂ Switching diode C ₂ Bypass capacitor UHF _{+ B} Power supply terminal for UHF circuit

Claims (1)

[Claims] 1. A VHF circuit for receiving a VHF signal and a UHF circuit for receiving a UHF signal are provided, and when a UHF signal is received,
In a U-V tuner device in which a frequency mixing circuit to which a VHF signal from the VHF circuit is input is used as an intermediate frequency amplification circuit of a UHF signal, a signal input terminal of the high frequency amplification circuit of the VHF circuit, The above
A diode connecting an anode to the power supply terminal is provided between the power supply terminal of the UHF circuit and the anode side of the diode is grounded via a bypass capacitor U- V tuner device.